How much calcium is too much?

Kapidolo Farms

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Something that annoys me about many nutritional studies is the way they quantity the nutrient as reported. "The tortoises consumed 2.6mg/kilo of body weight daily for 127 days."

The break down of this is you need to know the weight of the tortoise, the amount they ate and the amount of the nutrient in the amount they ate.

Have you noticed that most product labels for food list what in the food compared to an average diet, with an average amount of calories consumed? have you noticed that nearly all medication are pills per day etc. NOT based on your weight?

I found a study that reports of the result of calcium in the diet based on the amount of calcium in the foods as fed, on a fresh basis, not a dry weight basis.

I know I know, dry weight is so you can compare how much of the molecule of interest is in the food without water. But water is a nutrient too. Just because it's not a vitamin, essential protein, essential minerals, or fatty acid, we are all supposed to remove the water (mathematically) so we can compare food A to food B. There is some value in that, but the never-recognized fact is, water is the most essential nutrient.

The attached study looks at calcium in the diet of young leopard tortoises fed a calcium poor diet, so that calcium supplementation could be observed. They observed it a device that measured bone density, they observed it postmortem of some of the actual animals. They added calcium on a basis of grams/kilo of the food AS FED.

A quicky look by my cliff notes is...

Diet was Carrots, iceberg lettuce, cucumber, sweet pepper, tomatoes and hay ( with a multi vitamin/mineral supplement that had no calcium). A high water content diet. They added calcium at three levels, and no calcium at all, for a total of four groups. No 'sweet spot' is reported on. The no-calcium added diet still has some calcium in it. 60mg/155 gm of the diet AS FED (0.4 grams/kilo).

The supplement groups were more calcium for a total calcium AS FED of 2.9 grams/kilo, 8 grams/kilo and 23.3 grams/kilo. The first two group, no added calcium and low calcium showed sigh of poor shell development, while the two high groups showed calcium deposits developing in soft tissue (not good).

By guessing, 4-6 grams total calcium per kilo of food AS FED might be a good target, the authors do not suggest this.

The overall calcium phosphorus ratio will have an impact, and is not reported, so I'd have to sort out a high and low for what it might have been - by calculating the range that might be possible from the diet fed (mathematically), adding the amount that was in the supplement, and determining a ratio. I didn't do that.

The take away news is that they do suggest that adding calcium works, their range finding study is preliminary, it should be repeated, but it does give an actionable amount to aim for. An amount based on the foods offered AS FED, not dependent of how much the tortoises eat.

As a balance in thought, one local tortoise specialist vet has said that he does not believe he has ever seen a tortoise with soft tissue damage from excess calcium in the diet.
 

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Madkins007

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Not a vet, but I found a dosing formula for calcium/phosphorous, based on Dr. Mader's book- 1.3 to 8mg x Kcal (or, for every Calorie of food, there should be 1.3 to 8mg of calcium). Phosphorous should be between 0.5 to 1 times the calcium dose. (Mader, p. 287)

Calcium overdose? I would suspect that there are mechanisms in place to make this difficult in tortoises and other reptiles. Tortoises especially have been well documented self-selecting calcium-rich foods over what would presumably be 'tastier' options, so probably just pass the excess calcium- assuming adequate hydration.

Again, not a vet.

By the way, I have a whole page of this kind of junk at the Tortoise Library. The old Google version is easier for me to access and link, so... https://sites.google.com/site/tortoiselibrary/nutrition/guidelines-and-dosages
 

Kapidolo Farms

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Not a vet, but I found a dosing formula for calcium/phosphorous, based on Dr. Mader's book- 1.3 to 8mg x Kcal (or, for every Calorie of food, there should be 1.3 to 8mg of calcium). Phosphorous should be between 0.5 to 1 times the calcium dose. (Mader, p. 287)

Calcium overdose? I would suspect that there are mechanisms in place to make this difficult in tortoises and other reptiles. Tortoises especially have been well documented self-selecting calcium-rich foods over what would presumably be 'tastier' options, so probably just pass the excess calcium- assuming adequate hydration.

Again, not a vet.

By the way, I have a whole page of this kind of junk at the Tortoise Library. The old Google version is easier for me to access and link, so... https://sites.google.com/site/tortoiselibrary/nutrition/guidelines-and-dosages
Always glad to read your responses.
 

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